Use of Statistical Tests of Equivalence (Bioequivalence Tests) in Plant Pathology

Hypothesis tests currently used in plant pathology are almost always based on a null hypothesis of equal means. In this framework, the experimenter determines whether or not there is evidence that the means are, in fact, different. This framework makes sense for many common questions such as whether a new management technique gives an increase in yield over existing management techniques. But suppose, for example, that a disease management technique is so effective that an experimenter is interested in whether its use in the presence of disease achieves the same yield as in the absence of disease. In this case, a more appropriate null hypothesis would be that mean yields are different. Examples of questions in plant pathology for which a null hypothesis of equal treatment means is not suitable include (corresponding phrasing for one-sided questions is in parentheses as appropriate):